CompatibleInsetsUsage.swift

// in your UIViewController

func setupMySubview() {
  let topInset = compatibleSafeInsets.top
  let bottomInset = compatibleSafeInsets.bottom
  let leftInset = compatibleSafeInsets.left
  let rightInset = compatibleSafeInsets.right
  let height = view.frame.size.height - bottomInset - topInset
  let width = view.frame.size.width - leftInset - rightInset
  
  mySubview.frame = CGRect(x: leftInset, y: topInset, width: width, height: height)
}
 
// This is called on both iOS 11 and 10
override func viewDidLayoutSubviews() {
   setupMySubview()
}